3 files changed, 103 insertions, 3 deletions
diff --git a/llvm/include/llvm/Transforms/Scalar/SROA.h b/llvm/include/llvm/Transforms/Scalar/SROA.h
index 0bd592f0dae..4a321e75c68 100644
--- a/llvm/include/llvm/Transforms/Scalar/SROA.h
+++ b/llvm/include/llvm/Transforms/Scalar/SROA.h
@@ -130,7 +130,7 @@ private:
   bool splitAlloca(AllocaInst &AI, sroa::AllocaSlices &AS);
   bool runOnAlloca(AllocaInst &AI);
   void clobberUse(Use &U);
-  void deleteDeadInstructions(SmallPtrSetImpl<AllocaInst *> &DeletedAllocas);
+  bool deleteDeadInstructions(SmallPtrSetImpl<AllocaInst *> &DeletedAllocas);
   bool promoteAllocas(Function &F);
 };
 
diff --git a/llvm/lib/Transforms/Scalar/SROA.cpp b/llvm/lib/Transforms/Scalar/SROA.cpp
index 6de6c8cce2c..2d668f940fb 100644
--- a/llvm/lib/Transforms/Scalar/SROA.cpp
+++ b/llvm/lib/Transforms/Scalar/SROA.cpp
@@ -4243,8 +4243,9 @@ bool SROA::runOnAlloca(AllocaInst &AI) {
 ///
 /// We also record the alloca instructions deleted here so that they aren't
 /// subsequently handed to mem2reg to promote.
-void SROA::deleteDeadInstructions(
+bool SROA::deleteDeadInstructions(
     SmallPtrSetImpl<AllocaInst *> &DeletedAllocas) {
+  bool Changed = false;
   while (!DeadInsts.empty()) {
     Instruction *I = DeadInsts.pop_back_val();
     DEBUG(dbgs() << "Deleting dead instruction: " << *I << "\n");
@@ -4270,7 +4271,9 @@ void SROA::deleteDeadInstructions(
 
     ++NumDeleted;
     I->eraseFromParent();
+    Changed = true;
   }
+  return Changed;
 }
 
 /// \brief Promote the allocas, using the best available technique.
@@ -4312,7 +4315,7 @@ PreservedAnalyses SROA::runImpl(Function &F, DominatorTree &RunDT,
   do {
     while (!Worklist.empty()) {
       Changed |= runOnAlloca(*Worklist.pop_back_val());
-      deleteDeadInstructions(DeletedAllocas);
+      Changed |= deleteDeadInstructions(DeletedAllocas);
 
       // Remove the deleted allocas from various lists so that we don't try to
       // continue processing them.
diff --git a/llvm/test/Transforms/SROA/dead-inst.ll b/llvm/test/Transforms/SROA/dead-inst.ll
new file mode 100644
index 00000000000..b1d106df3e6
--- /dev/null
+++ b/llvm/test/Transforms/SROA/dead-inst.ll
@@ -0,0 +1,97 @@
+; SROA fails to rewrite allocs but does rewrite some phis and delete
+; dead instructions. Ensure that this invalidates analyses required
+; for other passes.
+; RUN: opt < %s -passes=bdce,sroa,bdce -o %t -debug-pass-manager 2>&1 | FileCheck %s
+; CHECK: Running pass: BDCEPass on H
+; CHECK: Running analysis: DemandedBitsAnalysis on H
+; CHECK: Running pass: SROA on H
+; CHECK: Invalidating all non-preserved analyses for: H
+; CHECK: Invalidating analysis: DemandedBitsAnalysis on H
+; CHECK: Running pass: BDCEPass on H
+; CHECK: Running analysis: DemandedBitsAnalysis on H
+; CHECK: Finished llvm::Function pass manager run.
+
+target datalayout = "e-m:e-i64:64-n32:64"
+target triple = "powerpc64le-grtev4-linux-gnu"
+
+%class.b = type { i64 }
+
+declare void @D(%class.b* sret, %class.b* dereferenceable(32)) local_unnamed_addr
+
+; Function Attrs: nounwind
+define hidden fastcc void @H(%class.b* noalias nocapture readnone, [2 x i64]) unnamed_addr {
+  %3 = alloca %class.b, align 8
+  %.sroa.0 = alloca i64, align 8
+  store i64 0, i64* %.sroa.0, align 8
+  %4 = extractvalue [2 x i64] %1, 1
+  switch i64 %4, label %6 [
+    i64 4, label %foo
+    i64 5, label %5
+  ]
+
+; <label>:5:
+  %.sroa.0.0..sroa_cast3 = bitcast i64* %.sroa.0 to i8**
+  br label %12
+
+; <label>:6:
+  %7 = icmp ugt i64 %4, 5
+  %.sroa.0.0..sroa_cast5 = bitcast i64* %.sroa.0 to i8**
+  br i1 %7, label %8, label %12
+
+; <label>:8:
+  %9 = load i8, i8* inttoptr (i64 4 to i8*), align 4
+  %10 = icmp eq i8 %9, 47
+  %11 = select i1 %10, i64 5, i64 4
+  br label %12
+
+; <label>:12:
+  %13 = phi i8** [ %.sroa.0.0..sroa_cast3, %5 ], [ %.sroa.0.0..sroa_cast5, %8 ], [ %.sroa.0.0..sroa_cast5, %6 ]
+  %14 = phi i64 [ 4, %5 ], [ %11, %8 ], [ 4, %6 ]
+  %15 = icmp ne i64 %4, 0
+  %16 = icmp ugt i64 %4, %14
+  %17 = and i1 %15, %16
+  br i1 %17, label %18, label %a.exit
+
+; <label>:18:
+  %19 = tail call i8* @memchr(i8* undef, i32 signext undef, i64 undef)
+  %20 = icmp eq i8* %19, null
+  %21 = sext i1 %20 to i64
+  br label %a.exit
+
+a.exit:
+  %22 = phi i64 [ -1, %12 ], [ %21, %18 ]
+  %23 = load i8*, i8** %13, align 8
+  %24 = sub nsw i64 %22, %14
+  %25 = bitcast %class.b* %3 to i8*
+  call void @llvm.lifetime.start.p0i8(i64 32, i8* nonnull %25)
+  %26 = icmp ult i64 %24, 2
+  br i1 %26, label %G.exit, label %27
+
+; <label>:27:
+  %28 = getelementptr inbounds i8, i8* %23, i64 undef
+  %29 = icmp eq i8* %28, null
+  br i1 %29, label %30, label %31
+
+; <label>:30:
+  unreachable
+
+; <label>:31:
+  call void @D(%class.b* nonnull sret %3, %class.b* nonnull dereferenceable(32) undef)
+  br label %G.exit
+
+G.exit:
+  call void @llvm.lifetime.end.p0i8(i64 32, i8* nonnull %25)
+  br label %foo
+
+foo:
+  ret void
+}
+
+; Function Attrs: nounwind readonly
+declare i8* @memchr(i8*, i32 signext, i64) local_unnamed_addr
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
+
+; Function Attrs: argmemonly nounwind
+declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture)